Further testing showed that the fix introduced in 7dfb8be11b5d
("btrfs: Round down values which are written for total_bytes_size") was
insufficient and it could still lead to discrepancies between the total_bytes in
the super block and the device total bytes. So this patch also ensures that
the difference between old/new sizes when shrinking/growing is also
rounded down. This ensure that we won't be substracting/adding a non-sectorsize
multiples to the superblock/device total sizees.

Fixes: 7dfb8be11b5d ("btrfs: Round down values which are written for 
total_bytes_size")
Signed-off-by: Nikolay Borisov <nbori...@suse.com>
---
 fs/btrfs/volumes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index fa779875bcfb..774b4168841a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2701,7 +2701,7 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 
        mutex_lock(&fs_info->chunk_mutex);
        old_total = btrfs_super_total_bytes(super_copy);
-       diff = new_size - device->total_bytes;
+       diff = round_down(new_size - device->total_bytes, fs_info->sectorsize);
 
        if (new_size <= device->total_bytes ||
            device->is_tgtdev_for_dev_replace) {
@@ -4399,7 +4399,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 
new_size)
        u64 diff;
 
        new_size = round_down(new_size, fs_info->sectorsize);
-       diff = old_size - new_size;
+       diff = round_down(old_size - new_size, fs_info->sectorsize);
 
        if (device->is_tgtdev_for_dev_replace)
                return -EINVAL;
-- 
2.7.4

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